1. Field of the Invention
The present invention relates to a driving control apparatus for a plurality of vibration driven (vibration wave) motors, which integrally controls the plurality of vibration driven motors (vibration wave motors).
2. Related Background Art
Conventionally, as a driving control apparatus for a plurality of vibration driven (vibration wave) motors, an apparatus as disclosed in Japanese Laid-Open Patent Application No. 64-60273 is known. This conventional apparatus has a frequency setting means for switching the frequency of a driving AC signal for a plurality of vibration driven (vibration wave) motors in accordance with each individual vibration driven motor and a distribution driving circuit for applying the driving signal to an arbitrarily selected vibration driven motor.
An apparatus disclosed in Japanese Laid-Open Patent Application No. 2-58510 comprises a plurality of detecting means for respectively detecting the vibration states of a plurality of vibration driven motors to stably drive them. The apparatus also has a switching means for feed back a plurality of signals generated from the detecting means to the CPU, thereby controlling the individual vibration driven motors.
In the conventional apparatus described above, however, the driving frequencies of the vibration driven motors are sequentially controlled by the CPU. For this reason, when the vibration state of a vibration driven motor suddenly varies from the resonance state due to a variation in load or the like, control is not performed in time. In this case, the vibration driven motor may deviate from the resonance frequency and suddenly stop.